The demands placed upon the worldwide air traffic system are changing at a rapid pace, because more aircraft are requiring the use of the same airspace and airports, placing greater demands on airport capacity. Due to energy demands and consumer requirements, commercial air carriers are increasingly utilizing smaller, more efficient aircraft in a “hub and spoke” arrangement, where a majority of flights initiate or terminate at an airport facility located near a large metropolitan area. Further, due to the fact the commercial air carriers are unable to meet the timing and convenience required by an increasing number of consumers, the air traffic system is being required to handle an increasing number of general aviation aircraft.
The increased number of flights operating from hub airports, both domestic and international, has resulted in significant air traffic congestion problems at these locations. A seemingly obvious solution to such congestion problems would be to merely add more runways, to add more taxiways, and to add more passenger terminals. Each of these potential solutions is fraught with problems. One such problem is that the real estate required for such additions is simply not available in many instances for additions to existing airports. For example, 468, homes adjacent to the Cleveland Hopkins Airport needed to be razed to add a third runway to that airport. Situations such as this raise the cost of adding even one new runway to inordinate levels.
Further, building entirely new airports creates significant other problems. One such problem is that an entirely new airport costs a large amount of taxpayer funds and takes a significant amount of time. For example, the new Denver International Airport cost over five billion dollars (US) and took longer than six years to complete. Another problem is that any new or proposed airport will likely be built even further from a respective metropolitan area than an existing airport, the added distance adding cost and inconvenience to most every traveler's plans.
Similarly, increasing the number of runways and passenger terminals to any airport greatly increases the complexity and time required for aircraft and passengers alike to navigate. As one can easily imagine, airports having only one runway and only one passenger terminal will require only a limited number of taxiways for the passage of aircraft to and from the passenger terminal. Also, as one can easily imagine, when the number of runways and passenger terminals is increased, the number of taxiways servicing those runways and passenger terminals exponentially increases. This increase alone comes with many problems.
Aircraft movement between a runway and a passenger terminal while on taxiways is a highly monitored activity with significant human involvement. Aircraft, regardless of their size, are built for safe and efficient travel during operation in the air. Aircraft are, however, large, ungainly land vehicles with significant visibility disabilities. Accordingly, aircraft pilots typically rely on air traffic controllers for orchestrating the guidance of their aircraft to and from runways on taxiways of large airports. As one can easily imagine, the task of individually directing the movement of a large aircraft, where the pilot is unable to see the extents of the aircraft, through a maze of taxiways is daunting task.
There are published taxi-paths that can be used as a reference for the air traffic controllers under particular circumstances, such during times of low visibility. It should be noted, however, that air traffic controllers often create their own taxi-paths for aircraft depending on their own experiences and their own interpretation of the current airport requirements. Accordingly, the actual taxi-paths used by aircraft may differ significantly from the published taxi-paths.
The increase in runways, aircraft, and taxiways brings additional requirements in the amount of time the aircraft spend traversing the distance between the runways and the passenger terminals. This additional time results in substantial additional fuel costs, substantial environmental impact, and substantial additional personnel costs. For example, aircraft engines are designed to develop efficient power while operating at a high altitude. While on the ground, these engines are inefficiently used to generate electrical power for the operation of the aircraft, used to power air conditioning systems, and used to propel the aircraft. Even through these tasks can be performed more efficiently by ground based power supply units, it is nearly impossible to have an aircraft attached to a ground power supply unit while the aircraft is traversing the distance between a runway and a passenger terminal.
Further, because the aircraft engines inefficiently produce power while on the ground, the aircraft produce large amounts of carbon dioxide (CO2) and other pollutants while in operation on the ground. Because of the effects that CO2, may have on climate change and the effect that the other pollutants may have on the air quality surrounding the airport, any amount of time that an aircraft spends in operation on the ground causes significant environmental impacts.
Additionally, a greater number of air traffic controllers are required because of the additional aircraft and the additional time an aircraft remains under the direction of a particular air traffic controller. Each air traffic controller can only direct a certain number of aircraft and/or aircraft in a certain region of an airport. Accordingly, when aircraft spend more time on traversing the distance between a runway and a passenger terminal, there are more aircraft in operation on the ground at any given time and more regions for aircraft to operate requiring more controllers. This additional controller workload also results in additional cost and potentially reduced safety.